General election 2019: what would have happened if we'd had PR?
The short answer is that it isn't possible to say what the result would have been under PR, and please beware of anyone who tells you otherwise!
The reason for the uncertainty is that voting patterns would be different under any form of proportional representation than they are under First Past the Post.
So, people would probably have voted differently under PR. But leaving that aside for a moment, it's possible to calculate how seats would have been allocated under more proportional voting systems.
This article published in The Conversation shows how the results might have looked under the Dutch system (which is almost completely proportional) and the German system (slightly less so).
In both cases, the Conservatives have more seats than Labour, but they don't win an outright majority, and would have to go into a coalition with another party in order to form a government. Alternatively, it's just possible that Labour could potentially have formed a coalition...
In any case, PR would have given us a government in which seats matched votes, and in which it was possible to hold the government to account, in a way which can't be done when a government has a large overall majority.